1. Field of the Invention
The present invention relates to a semiconductor device, for example, a semiconductor storage device and a method of producing the semiconductor device.
2. Background Art
Recently, there is an increasing demand to form a finer pattern in order to deal with a finer design rule and higher integration of the semiconductor device. Particularly, in applicable design rules at the time of development, a relatively small design rule is applied to the semiconductor storage device for the purpose of large capacity. The semiconductor storage device has two regions in the same plane, that is, a memory cell region and a peripheral region except for the memory cell region in the same plane. Generally, the memory cell region differs from the peripheral region in the applied design rule. The memory cell region includes a bit line or a word line, which is connected to a memory cell (storage element). In the memory cell region, usually the design rule is set to a minimum value (hereinafter simply referred to as F) that is permitted at the time of development in order to enhance an integration degree. On the other hand, the peripheral region includes an interconnection which connects the memory cell and a driving element of the memory cell. In the peripheral region, it is not always necessary that the design rule be set to the minimum value F, but the design rule is frequently set to a value larger than the minimum value F.
In order to optimize an exposure condition, there is well known a method of performing exposure with deformed illumination, that is, exposure with exposure light deformed by an aperture interposed between an exposure light source and a reticle (for example, see Japanese Patent Application Laid-Open No. 2001-135570). The method can improve resolution and a Depth Of Focus (DOF). However, in cases where the aperture having a shape of FIG. 4 disclosed in Japanese Patent Application Laid-Open No. 2001-135570 is used, sometimes the resolution and DOF are degraded to a crosswise pattern compared with the usual exposure while the resolution and DOF are improved to a longitudinal pattern.